The air vacuum pump is a venturi-type AC pump that eliminates moisture from air conditioning systems, making it safe and easy to add refrigerant. The atmosphere vacuum pump is easy to operate and pulls full vacuum within two minutes of being linked to an air series. Contains 1/2 in. ACME (R134a) and R12 connectors.
Air-powered vacuum pumps work when compressed air passing through an orifice increases its velocity and lowers its air pressure. Ambient atmosphere is used through channels 
in the generator, creating suction and vacuum. The atmosphere stream exits through the exhaust. … These procedures require vacuum pumps.